The present invention relates to devices for mixing together various components which are combined to form a given plastic. The device of the invention is particularly suitable for mixing the various components of a phenolic foam material which is ejected onto a moving platen for subsequent foaming into material such as thermal insulation board.
Devices of this type are subject to stringent operating requirements. Thus, when dealing with materials of the above type fast production rates are essential. Such product rates typically involve a "creaming" time of the mixed chemical components which is on the order of 2-3 seconds, with subsequent blowing being completed in the following 20-30 seconds. Because of this type of fast production rate, the device is subjected to severe operating requirements particularly with respect to prevention of setting and build-up of the materials which are mixed by the device as well as with respect to failure of seals and maintenance of essential cooling and lubrication of moving parts.
It has not yet been possible with conventional devices to fulfill these requirements in a fully adequate manner. The conventional devices suffer from undesirably large down times due to bearing failures and plugging during which various parts thereof must be disassembled, cleaned, and reassembled or during which certain parts must be replaced. Thus, the conventional mixing devices suffer not only from the drawback of frequent and undesirably long down times.